Is there any research on neural networks with multiple outputs for hierarchical label classification?
Sounds like a very interesting idea! I dont know existing work on the idea, but the implementation should be pretty simple with separate training with tied weights. It should be noted however that such behaviour occurs naturally in CNN's already. (See: http://www.cs.toronto.edu/~guerzhoy/321/lec/W07/HowConvNetsSee.pdf)